Feather pecking is quite similar to a stereotypy, and dopamine may have a role in the performance of stereotypies in fowl. Two experiments were conducted to examine the effects of the administration of a dopamine D2 receptor antagonist (haloperidol) on the general and feather pecking behaviours of laying hens. In the first experiment the birds were either injected with various concentrations haloperidol or saline (control) and their behaviour 30 minutes before and after the injection were recorded. A dosage of 1.0mg/kg of body weight sedated the hens, while dosages less than or equal to 0.50 mg/kg were ineffective. Therefore, the proper dosage is ranges between 0.50 to 1.0 mg/kg of haloperidol. In a second experiment, feather pecking and aggressive pecking were recorded for the 50-minute period before and after the injection of 0.50mg/kg of haloperidol or saline. Only feather pecking was significantly reduced with the administration of 0.50mg/kg of haloperidol, while it was ineffective at reducing aggressive pecking. Overall, the study verifies that feather pecking is influenced by the dopamine system.